Showing papers in "International Journal of Applied Mechanics and Engineering in 2020"

Mechanical Vapour Compression Refrigeration System: Review Part 1: Environment Challenge

Abstract: In Australia and others developed countries, concerns about global warming have increased, and these concerns influence the use of refrigerants as working fluids in mechanical vapour compression refrigeration systems. One of the most important aspects of refrigerant selection is to reduce its impact on the environment and the ozone layer. This paper provides a comprehensive review of various theoretical and experimental studies which have been carried out on air conditioning and refrigeration applications to investigate the effect of refrigerants on the environment. The analysis in this paper reveals that alternative refrigerants are the most suitable working fluids that can be used in refrigeration systems to meet the needs of the environment. This study also suggests that natural types of refrigerants such as water, carbon dioxide, and hydrocarbon will play a significant role in protecting the environment and providing alternative friendly refrigerants to be used in refrigeration and air conditioning systems.

Effect of Convective Heat and Mass Conditions in Magnetohydrodynamic Boundary Layer Flow with Joule Heating and Thermal Radiation

Abstract: Abstract A free convection viscous MHD flow over a semi-infinite vertical sheet with convective heat and mass conditions has been considered. The effects of thermal radiation, chemical reaction and Joule heating on flow are also accounted. The governing nonlinear partial differential equations have been transformed into a set of highly non-linear coupled ordinary differential equations (ODEs) using appropriate similarity transformations. Numerical solutions of transformed equations are obtained by employing the 5th order Runge-Kutta Fehlberg technique followed by the shooting technique. The influences of different flow parameters on the momentum, energy and mass field are discussed and shown graphically. Results reveal that temperature and concentration profiles enhance due to increasing heat and mass Biot number parameters.

Numerical investigation on the transition of fluid flow characteristics through a rotating curved duct

Abstract: Abstract Time-dependent flow investigation through rotating curved ducts is utilized immensely in rotating machinery and metal industry. In the ongoing exploration, time-dependent solutions with flow transition through a rotating curved square duct of curvature ratio 0.009 have been performed. Numerical calculations are carried out for constant pressure gradient force, the Dean number Dn = 1000 and the Grashof number Gr=100 over a wide range of the Taylor number values –1500 ≤ Tr ≤ 1500 for both positive and negative rotation of the duct. The software Code::Blocks has been employed as the second programming tool to obtain numerical solutions. First, time evolution calculations of the unsteady solutions have been performed for positive rotation. To clearly understand the characteristics of regular and irregular oscillations, phase spaces of the time evolution results have been enumerated. Then the calculations have been further attempted for negative rotation and it is found that the unsteady flow shows different flow instabilities if Tr is increased or decreased in the positive or in the negative direction. Two types of flow velocities such as axial flow and secondary flow and temperature profiles have been exposed, and it is found that there appear two- to four-vortex asymmetric solutions for the oscillating flows for both positive and negative rotation whereas only two-vortex for the steady-state solution for positive rotation but four-vortex for negative rotation. From the axial flow pattern, it is observed that two high-velocity regions have been created for the oscillating flows. As a consequence of the change of flow velocity with respect to time, the fluid flow is mixed up in a great deal which enhances heat transfer in the fluid.

A Numerical Study of Dissipative Chemically Reactive Radiative MHD Flow Past a Vertical Cone with Nonuniform Mass Flux

Abstract: Abstract A computational model is presented to explore the properties of heat source, chemically reacting radiative, viscous dissipative MHD flow of an incompressible viscous fluid past an upright cone under inhomogeneous mass flux. A numerical study has been carried out to explore the mass flux features with the help of Crank-Nicolson finite difference scheme. This investigation reveals the influence of distinct significant parameters and the obtained outputs for the transient momentum, temperature and concentration distribution near the boundary layer is discussed and portrayed graphically for the active parameters such as the Schmidt number Sc, thermal radiation Rd, viscous dissipation parameter ɛ, chemical reaction parameter λ, MHD parameter M and heat generation parameter Δ. The significant effect of parameters on shear stress, heat and mass transfer rates are also illustrated.

Rheological Behavior of Fly Ash Suspension with Additive for Hydraulic Conveyance

Abstract: Abstract In the present work, rheological behaviour of a fine particulate fly ash slurry suspension is studied with and without addition of an additive. Rheological experiments are performed for the range of shear rate from 50 to 200 s1. Sodium sulfate is used as an additive in the fraction of 0.2, 0.4 and 0.6% (by weight). Addition of sodium sulfate to the fly ash slurry suspension leads to an improvement of its rheological characteristics. A reduction in relative viscosity and pressure drop is more pronounced with the addition of sodium sulfate in proportion of 0.4%, while marginal with 0.2 and 0.6% (by weight). The analysis reveals that the fly ash suspension has a potential to for being transported in a slurry pipeline with higher concentration and minimum energy consumption.

Mixed Convection on MHD Flow with Thermal Radiation, Chemical Reaction and Viscous Dissipation Embedded in a Porous Medium

Abstract: Abstract In this paper, a theoretical analysis has been made to study the effect of mixed convection MHD oscillatory Couette flow in a vertical parallel channel walls embedded in a porous medium in the presence of thermal radiation, chemical reaction and viscous dissipation. The channel walls are subjected to a constant suction velocity and free stream velocity is oscillating with time. The channel walls are embedded vertically in a porous medium. A magnetic field of uniform strength is applied normal to the vertical channel walls. The nonlinear and coupled partial differential equations are solved using multi parameter perturbation techniques. The effects of physical parameters, viz., the radiation absorption parameter, Prandtl number, Eckert number, dynamic viscosity, kinematic viscosity, permeability of porous medium, suction velocity, Schmidt number and chemical reaction parameter on flow variables viz., temperature, concentration and velocity profile have been studied. MATLAB code is used to analyze theoretical facts. The important results show that an increment in the radiation absorption parameter and permeability of porous medium results in an increment of the temperature profile. Moreover, an increment in the Prandtl number, Eckert number and dynamic viscosity results in a decrement of the temperature profile. An increment in suction velocity results in a decrement of the velocity profile. An increment in the Schmidt number, chemical reaction parameter and kinematic viscosity results in a decrement of the concentration profile.

Numerical Analysis of Deformation and Flow in the Proximal Area of the Urethra

Abstract: Abstract Pathological conditions of a male urethra, including fibrosis, have a mechanical background along the entire length of the urethra. They may be caused by excessive deformation of the urethra locally or globally. The condition of prolonged overload causes abnormal tissue remodelling and, consequently, the formation of a thick layer of scar tissue differentiated from the connective tissue of the urethra. This tissue, which has higher mechanical properties, is not highly deformable and therefore, causes a decrease in the diameter of the urethra, which results in conditions that disturb the natural flow of urine. In this paper, it was decided to determine the deformation conditions in the proximal part of the urethra. The study was conducted in three main stages. Transverse sections of the animal urethral tissues were prepared in order to examine mechanical properties and perform histological examinations. On the basis of these examinations, material models which fitted best for the experimental results were sought. Material constants of the Mooney-Rivlin material model with the best fit ratio were determined for further research. On the basis of histological photographs, a geometrical and numerical model of the urethra was developed. The urethra was tested in a flat state of deformation. The strain and stress fields of the Caucha tensor were examined. The methodology of testing the dynamics of the urine flow in the highly deformable urethra was proposed. This is important for the analysis of the influence of at excessive pressure on pathological tissue remodelling leading to fibrosis.

Analytical Solutions for a General Mixed Boundary Value Problem Associated with Motions of Fluids with Linear Dependence of Viscosity on the Pressure

Abstract: Abstract An unsteady flow of incompressible Newtonian fluids with linear dependence of viscosity on the pressure between two infinite horizontal parallel plates is analytically studied. The fluid motion is induced by the upper plate that applies an arbitrary time-dependent shear stress to the fluid. General expressions for the dimensionless velocity and shear stress fields are established using a suitable change of independent variable and the finite Hankel transform. These expressions, that satisfy all imposed initial and boundary conditions, can generate exact solutions for any motion of this type of the respective fluids. For illustration, three special cases with technical relevance are considered and some important observations and graphical representations are provided. An interesting relationship is found between the solutions corresponding to motions induced by constant or ramptype shear stresses on the boundary. Furthermore, for validation of the results, the steady-state solutions corresponding to oscillatory motions are presented in different forms whose equivalence is graphically proved.

The Effect of Modulation on Heat Transport by a Weakly Nonlinear Thermal Instability in the Presence of Applied Magnetic Field and Internal Heating

Abstract: Abstract The present paper deals with a weakly nonlinear stability problem under an imposed time-periodic thermal modulation. The temperature has two parts: a constant part and an externally imposed time-dependent part. We focus on stationary convection using the slow time scale and quantify convective amplitude through the real Ginzburg-Landau equation (GLE). We have used the classical fourth order Runge-Kutta method to solve the real Ginzburg-Landau equation. The effect of various parameters on heat transport is discussed through GLE. It is found that heat transport analysis is controlled by suitably adjusting the frequency and amplitude of modulation. The applied magnetic field (effect of Ha) is to diminish the heat transfer in the system. Three different types of modulations thermal, gravity, and magnetic field have been compared. It is concluded that thermal modulation is more effective than gravity and magnetic modulation. The magnetic modulation stabilizes more and gravity modulation stabilizes partially than thermal modulation.

Heat and Mass Transfer Effects on MHD Flow Past an Inclined Porous Plate in the Presence of Chemical Reaction

Abstract: Abstract The impact of heat and mass transfer effects on an MHD flow past an inclined porous plate in the presence of a chemical reaction is investigated in this study. An effort has been made to explain the Soret effect and the influence of an angle of inclination on the flow field, in the presence of the heat source, chemical reaction and thermal radiation. The momentum, energy and concentration equations are derived as coupled second order partial differential equations. The model is non-dimensionalized and shown to be controlled by a number of dimensionless parameters. The resulting dimensionless partial differential equations can be solved by using a closed analytical method. Numerical results for pertaining parameters, such as the Soret number (Sr), Grashof number (Gr) for heat and mass transfer, the Schmidt number (Sc), Prandtl number (Pr), chemical reaction parameter (Kr), permeability parameter (K), magnetic parameter (M), skin friction (τ), Nusselt number (Nu) and Sherwood number (Sh) on the velocity, temperature and concentration profiles are presented graphically and discussed qualitatively.

The complex Ginzburg Landau model for an oscillatory convection in a rotating fluid layer

Abstract: Abstract A weakly nonlinear thermal instability is investigated under rotation speed modulation. Using the perturbation analysis, a nonlinear physical model is simplified to determine the convective amplitude for oscillatory mode. A non-autonomous complex Ginzburg-Landau equation for the finite amplitude of convection is derived based on a small perturbed parameter. The effect of rotation is found either to stabilize or destabilize the system. The Nusselt number is obtained numerically to present the results of heat transfer. It is found that modulation has a significant effect on heat transport for lower values of ωf while no effect for higher values. It is also found that modulation can be used alternately to control the heat transfer in the system. Further, oscillatory mode enhances heat transfer rather than stationary mode.

MHD mixed convection in copper-water nanofluid filled lid-driven square cavity containing multiple adiabatic obstacles with discrete heating

Abstract: Abstract The objective of the present work is to investigate the influence of nanoparticles of copper within the base fluid (water) on magneto-hydrodynamic mixed-convection flow in a square cavity with internal generation. A control finite volume method and SIMPLER algorithm are used in the numerical calculations. The geometry is a lid-driven square cavity with four interior square adiabatic obstacles. A uniform heat source is located in a part of the left wall and a part of the right wall of the enclosure is maintained at cooler temperature while the remaining parts of the two walls are thermally insulated. Both the upper and bottom walls of the cavity are considered to be adiabatic. A comparison with previously published works shows a very good agreement. It is observed that the Richardson number, Ri, significantly alters the behavior of streamlines when increased from 0.1 to 100.0. Also, the heat source position parameter, D, significantly changes the pattern of isotherms and its strength shifted when D moves from 0.3 to 0.7.

Mixed Convection in MHD Flow and Heat Transfer Rate Near a Stagnation-Point on a Non-Linear Vertical Stretching Sheet

Abstract: Abstract This work investigates the mixed convection in a Magnetohydrodynamic (MHD) flow and heat transfer rate near a stagnation-point region over a nonlinear vertical stretching sheet. Using a similarity transformation, the governing equations are transformed into a system of ordinary differential equations which are solved numerically using the fourth order Runge-Kutta method with shooting technique. The influence of pertinent flow parameters on velocity, temperature, surface drag force and heat transfer rate are computed and analyzed. Graphical and tabular results are given to examine the nature of the problem. The heat transfer rate at the surface increases with the mixed convection.

MHD Free Convection-Radiation Interaction in a Porous Medium - Part II: Soret/Dufour Effects

Abstract: This paper is focused on the study of two dimensional steady magnetohydrodynamics heat and mass transfer by laminar free convection from a radiative horizontal circular cylinder in a nonDarcy porous medium by taking account the Soret/Dufour effects. The boundary layer equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller–Box finite-difference scheme. Numerical results obtained for the velocity, temperature and concentration distributions, as well as the local skin friction, Nusselt number and Sherwood number for several values of the parameters, namely the buoyancy ratio parameter, Prandtl number, Forchheimer number, magnetohydrodynamic body force parameter, Soret and Dufour numbers. The dependency of the thermophysical properties has been discussed on the parameters and showed graphically. Increasing Forchheimer inertial drag parameter reduces velocity but elevates temperature and concentration. Increasing Soret number and simultaneously reducing Dufour number greatly boosts the local heat transfer rate at the cylinder surface. A comparative study between the previous published and present results in a limiting sense is found in an excellent agreement.

The characteristics of selected triaxiality measures of the stresses for a C(T) specimen dominated by the plane strain state

Abstract: Abstract The paper presents a comprehensive analysis of the stress field and selected triaxiality parameters near the crack tip for C(T) specimen dominated by the plane strain state using the finite element method. It includes some theoretical information about elastic-plastic fracture mechanics, the basics of the FEM modeling and presentation of the numerical results. The FEM analysis includes calculations with large strain assumptions. The influence of the external load and crack length is discussed. Additional elements of the paper are a qualitative assessment of the size of plastic zones and the crack tip opening displacement.

Analytical Model of the Two-Mass Above Resonance System of the Eccentric-Pendulum Type Vibration Table

Abstract: Abstract The article deals with atwo-mass above resonant oscillatory system of an eccentric-pendulum type vibrating table. Based on the model of a vibrating oscillatory system with three masses, the system of differential equations of motion of oscillating masses with five degrees of freedom is compiled using generalized Lagrange equations of the second kind. For given values of mechanical parameters of the oscillatory system and initial conditions, the autonomous system of differential equations of motion of oscillating masses is solved by the numerical Rosenbrock method. The results of analytical modelling are verified by experimental studies. The two-mass vibration system with eccentric-pendulum drive in resonant oscillation mode is characterized by an instantaneous start and stop of the drive without prolonged transient modes. Parasitic oscillations of the working body, as a body with distributed mass, are minimal at the frequency of forced oscillations.

Effect of Rayleigh Number on Internal Eccentricity in a Heated Horizontal Elliptical Cylinder to its Coaxial Square Enclosure

Abstract: Abstract This paper deals with numerical investigation of a natural convective flow in a horizontal annular space between a heated square inner cylinder and a cold elliptical outer cylinder with a Newtonian fluid. Uniform temperatures are imposed along walls of the enclosure. The governing equations of the problem were solved numerically by the commercial code Fluent, based on the finite volume method and the Boussinesq approximation. The effects of Geometry Ratio GR and Rayleigh numbers on fluid flow and heat transfer performance are investigated. The Rayleigh number is varied from 103 to 106. Throughout the study the relevant results are presented in terms of isotherms, and streamlines. From the results, we found that the increase in the Geometry Ratio B leads to an increase of the heat transfer coefficient. The heat transfer rate in the annulus is translated in terms of the average Nusselt numbers along the enclosure’s sides. Tecplot 7 program was used to plot the curves which cleared these relations and isotherms and streamlines which illustrate the behavior of air through the channel and its variation with other parameters. The results for the streamlines, isotherms, local and average Nusselt numbers average Nusselt numbers are compared with previous works and show good agreement.

Elastic Buckling Analysis of Uniaxially Compressed CCCC Stiffened Isotropic Plates

Abstract: Abstract This paper reports a research study that investigated buckling of stiffened rectangular isotropic plates elastically restrained along all the edges (CCCC) under uniaxial in-plane load, using the work principle approach. The stiffeners were assumed to be rigidly connected to the plate. Analyses for critical buckling of stiffened plates were carried out by varying parameters, such as the number of stiffeners, stiffness properties and aspect ratios. The study involved a theoretical derivation of a peculiar shape function by applying the boundary conditions of the plate on Taylor Maclaurin’s displacement function and substituted on buckling equation derived to obtain buckling solutions. The present solutions were validated using a trigonometric function in the energy method from previous works. Coefficients, K, were compared for various numbers of stiffeners and the maximum percentage difference obtained within the range of aspect ratios of 1.0 to 2.0 is shown in Figs 2 - 7. A number of numerical examples were presented to demonstrate the accuracy and convergence of the current solutions.

Performance of Four Different Nanoparticles in Boundary Layer Flow Over a Stretching Sheet in Porous Medium Driven by Buoyancy Force

Abstract: Abstract This contemporary work explores the theoretical analysis of energy transfer performance of distinct nanoparticles (silver, copper, aluminium oxide and titanium oxide) adjacent to a moving surface under the influence of a porous medium which is driven by the buoyancy force. A mathematical model is presented which is converted to similarity equations by employing similarity transformation. The condensed nonlinear equations were approximated by the iterative method called RKF 45th-order. The flow and energy transference characteristics are explained through graphs and tabulated values. The notable findings are: silver- water is an appropriate nanofluid for enhancing the thermal conductivity of the base fluid. Titanium oxide – water shows a lower fluid flow movement due to porosity.

Effect of Magnetic Field Dependent Viscosity on the Unsteady Ferrofluid Flow Due to a Rotating Disk

Abstract: Abstract The effect of magnetic field dependent viscosity on ferrofluid flow due to a rotating disk is studied in the presence of a stationary magnetic field. The results for velocity profiles for various values of MFD viscosity parameter are shown graphically. These results are compared with the ordinary case when the applied magnetic field is absent. Besides, the shear stress on the wall of the disk and its surface is calculated numerically.

A review: differential transform method for semi-analytical solution of differential equations

Abstract: Abstract In this article, the semi-analytical method known as the Differential Transform Method (DTM) for solving different types of differential equations is reviewed. First, basic definitions and formulas of DTM and Differential Transform-Padé approximation (DTM-Padé), which are used to increase the convergence and accuracy of DTM approximations, are discussed. Then both techniques of DTM and DTM-Padé, which have been successfully applied to partial differential equations, as well as the application of these methods in fluid mechanic and heat transfer are presented. In addition, the extension of DTM for integral differential equations and the fuzzy differential transformation method (FDTM) for fuzzy problems are discussed.

Hybrid Sandwich Panels: A Review

Abstract: Abstract A high specific stiffness, high specific strength, and tailoring the properties for specific application have attracted the attention of the researchers to work in the field of laminated composites and Sandwich structures. Rapid use of these laminated composites and Sandwich structures necessitated the development of new theories that suitable for the bending, buckling and vibration analysis. Many articles were published on free vibration of beams, plates, shells laminated composites and sandwich structures. In this article, a review on free vibration analysis of shear deformable isotropic beams, plates, shells, laminated composites and sandwich structures based on various theories and the exact solution is presented. In addition to this, the literature on finite element modeling of beams, plates, shells laminated composites and sandwich structures based on classical and refined theories is also reviewed. The present article is an attempt to review the available literature, made in the past few decades on free flexural vibration response of Fiber Metal laminated Composites and Sandwich panels using different analytical models, numerical techniques, and experimental methods.

Transient Heat and Mass Transfer of Hydromagnetic Effects on the Flow Past a Porous Medium with Movable Vertical Permeablesheet

Abstract: Abstract An unsteady flow of heat and species transport through a porous medium in an infinite movable vertical permeable flat surface is considered. The hydromagnetic chemical reactive fluid flow is stimulated by the thermal and solutant convection, and propelled by the movement of the surface. The formulated nonlinear flow equations in time space are solved analytically by asymptotic expansions to obtain solutions for the flow momentum, energy and chemical concentration for various thermo-physical parameters. The existence of flow characteristic is defined with the assistance of the flow parameters. In the study, the impact of some pertinent flow terms is reported and discussed. The study revealed that the species boundary layer increases with a generative chemical reaction and decreases with a destructive chemical reaction. Also, arise in the generative species reaction term reduces the flow momentum for the cooling surface. The impact of other flow governing parameters is displayed graphically as well as the fluid wall friction, wall energy and species gradients. The results of this study are important in chemical thermal engineering for monitoring processes to avoid solution blow up.

Effects of Radiation and Eckert Number on MHD Flow with Heat Transfer Rate Near a Stagnation Point Over a Non-Linear Vertical Stretching Sheet

Abstract: Abstract This work investigates the effects of radiation and Eckert number on an MHD flow with heat transfer rate near a stagnation-point region over a nonlinear vertical stretching sheet. Using a similarity transformation, the governing equations are transformed into a system of ordinary differential equations which are solved numerically using the sixth order Runge-Kutta method with shooting technique. Tabular and graphical results are provided to examine the physical nature of the problem. Heat transfer rate at the surface decreases with radiation, Eckert number and as radiation increases, the flow temperature also increases for velocity ratio parameters ɛ <1 and ɛ >1.

Optimization of Heat Transfer Properties of Nanofluid Flow Over a Shrinking Surface Through Mathematical Modeling

Abstract: Abstract In the current study, a three dimensional incompressible magnetohydrodynamic (MHD) nanofluid flow over a shrinking surface with associated thermal buoyancy, thermal radiation, and heating absorption effects, as well as viscous dissipation have been investigated. The model has been represented in a set of partial differential equations and is transformed using suitable similarity transformations which are then solved by using the finite element method through COMSOL. The results for velocity and temperature profiles are provided for various values of the shrinking parameter, Biot’s number, heat generation/absorption parameter, thermal Grashof number, nanoparticle volume fraction, permeability parameter, magnetic parameter and radiation parameter.

The Effect of Magnetic Field Dependent Viscosity on Ferromagnetic Convection in a Rotating Sparsely Distributed Porous Medium - Revisited

Abstract: Abstract The effect of magnetic field dependent (MFD) viscosity on the thermal convection in a ferrofluid layer saturating a sparsely distributed porous medium has been investigated by using the Darcy-Brinkman model in the simultaneous presence of a uniform vertical magnetic field and a uniform vertical rotation. A correction is applied to the study of Vaidyanathan et al. [11] which is very important in order to predict the correct behavior of MFD viscosity. A linear stability analysis has been carried out for stationary modes and oscillatory modes separately. The critical wave number and critical Rayleigh number for the onset of instability, for the case of free boundaries, are determined numerically for sufficiently large values of the magnetic parameter M1. Numerical results are obtained and are illustrated graphically. It is shown that magnetic field dependent viscosity has a destabilizing effect on the system for the case of stationary mode and a stabilizing effect for the case of oscillatory mode, whereas magnetization has a destabilizing effect.

Using the ERFI Function in the Problem of the Shape Optimization of the Compressed Rod

Abstract: Abstract The shape of the optimal rod determined in the work meets the condition of mass conservation in relation to the reference rod. At the same time, this rod shows a significant increase in resistance to axial force. In the examples presented, this increase was 80% and 117%, respectively, for rods with slenderness of 125 and 175. A practical benefit from the use of compression rods of the proposed shapes is clearly visible. The example presented in this publication shows how great the utility in the structural mechanics can be, resulting from the applications of complex analysis (complex numbers). This approach to many problems can find its solutions, while they are lacking in the real numbers domains. What is more, although these are operations on complex numbers, these solutions have often their real representations, as the numerical example shows. There are too few applications of complex numbers in the technique and science, therefore it is obvious that the use of complex analysis should have an increasing range. One of the first people to use complex numbers was Girolamo Cardano. Cardano, using complex numbers, was solving cubic equations, unsolvable to his times – as the famous Franciscan and professor of mathematics Luca Pacioli put it in his paper Summa de arithmetica, geometria, proportioni et proportionalita (1494). It is worth mentioning that history has given Cardano priority in the use of complex numbers, but most probably they were discovered by another professor of mathematics – Scipione del Ferro (cf. [1]). We can see, that already then, they were definitely important (complex numbers).

A New Approach for Study the Electrohydrodynamic Oscillatory Flow Through a Porous Medium in a Heating Compliant Channel

Abstract: Abstract The governing equations of an electrohydrodynamic oscillatory flow were simplified, using appropriate nondimensional quantities and the conversion relationships between fixed and moving frame coordinates. The obtained system of equations is solved analytically by using the regular perturbation method with a small wave number. In this study, modified non-dimensional quantities were used that made fluid pressure in the resulting equations dependent on both axial and vertical coordinates. The current study is more realistic and general than the previous studies in which the fluid pressure is considered functional only in the axial coordinate. A new approach enabled the author to find an analytical form of fluid pressure while previous studies have not been able to find it but have found only the pressure gradient. Analytical expressions for the stream function, electrical potential function and temperature distribution are obtained. The results show that the electrical potential function decreases by the increase of the Prandtl number, secondary wave amplitude ratio and width of the channel.

Heat Transfer Enhancement from a Heated Plate with Hemispherical Convex Dimples by Forced Convection Along with a Cross Flow Jet Impingement

Abstract: Abstract In the present study, heat transfer from a small three dimensional rectangular channel due to turbulent jet impinging from a nozzle normal to the main flow at the inlet has been investigated. Hemispherical convex dimples are attached to the bottom plate from where heat transfer calculations are to be performed. Numerical simulations were performed using the finite volume method with SST k– ω turbulence model. The duct and nozzle Reynolds number are varied in the range of 10000 ≤ ReD ≤ 50000 and 6000 ≤ Red ≤ 12000, respectively. Different nozzle positions (X/D = 10.57, 12.88, 15.19) along the axial direction of the rectangular duct have been considered. It has been found that higher heat transfer is observed at X/D = 10.57 as compared to the other positions. The heat transfer enhancements with and without cross-flow effects have also been compared. It has been shown that the heat transfer rate with cross-flow is found to be much higher than that without cross-flow. Also, the effect of dimples on the heated surface on heat transfer was investigated. The heat transfer is found to be greater in the presence of a dimpled surface than a plane surface.

Outcome of Nanofluid Flow Containing Arbitrary Shape Nanoparticles Induced by a Permeable Stretching Sheet

Abstract: Abstract In this work we have discussed the impact of thermal radiation on heat transfer to nanofluid flow over an unsteady permeable stretching sheet using various types of arbitrary shape nanoparticles of Copper (Cu), Silver (Ag), Alumina (Al2O3), and Titania Oxide (TiO2) in the base fluid. Suitable transformations have been employed to build ODEs from the partial differential equations. Numerical results are therefore obtained particularly for cylindrical shape and spherical shape nanoparticles. Our analysis substantiates that the velocity and temperature profiles increases with enhanced thermal radiation parameter. Further, Nusselt number is more advanced for the nanofluid that contains cylindrical shape nanoparticles as compared to spherical shape nanoparticles.